This invention relates to the field of isolation and containment of hazardous materials and sensitive materials. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).
Numerous substances must be isolated from the atmosphere and from contact with people, yet must be accessible for manipulation by humans. These materials include radioactive substances, toxic substances, and certain biological materials. Hoods and gloveboxes are often used to contain and isolate these materials when they must be handled, though certain highly radioactive materials must be isolated behind leaded glass as much as 50 cm thick and handled by remotely operated mechanical manipulators. The most common containment or isolation apparatus is a laboratory hood having an entirely open front and an exhaust fan connected to the rear or top of the hood. The fan causes air to flow into the hood from the open front toward the fan connection, thus tending to sweep material away from a technician facing the open front of the hood.
Gloveboxes are well known enclosures for isolating hazardous materials, particularly when radioactive materials must be handled. These boxes are completely sealed from the atmosphere and have gloves with long cuffs, or extensions, located inside the enclosure and connected to a wall of the enclosure. A small air flow through the box is usually maintained and both air entering the box and air leaving the box passes through HEPA filters. A technician inserts his hands and forearms into the cuffed gloves and then can manipulate materials and apparatus inside the box. Where the need for isolation is less critical, "open-front gloveboxes," or open-front containment boxes, may be used. Though the term "open-front glovebox" is inaccurate, it is commonly used. For example, a standard glovebox may be used for radioactive substances in the form of powders while an open-front glovebox is used for radioactive solutions. An open-front containment box is an enclosure having an opening without gloves attached to it through which a technician may insert his hands and, if necessary, his forearms to handle material within the box. The technician will normally be wearing protective clothing, such as gloves and a smock. An open-front glovebox is much more convenient to use than a conventional glovebox and its use allows a technician to work more rapidly. An open-front glovebox is normally maintained at a pressure slightly below atmospheric pressure by means of a fan which exhausts the air passing through the glovebox to the atmosphere. In most cases, a filter is provided at some point between the fan inlet and outlet to prevent toxic material which is pulled from the glovebox by the fan from entering the atmosphere.
In the manufacture of pharmaceuticals and electronic components such as chips, it is necessary to protect the product from airborne contamination. This is normally accomplished by working in "clean rooms" in which the air pressure is greater than atmospheric pressure so that air flows out of the rooms. The air provided to a clean room must be filtered and people entering a clean room must completely cover their normal clothing with smocks or "bunny suits" which do not shed particulate matter and often must wear face masks. For certain small scale operations, a containment box which is operated at a positive pressure by means of supplying clean air to it may be used instead of a clean room.
The present invention is useful in either situation: where the material handled is toxic or where the material handled must be protected from atmospheric contamination. It is applicable to both conventional gloveboxes and open-front containment or isolation enclosures. It was developed in the course of design of a facility requiring several hundred open-front gloveboxes.